Yes I too am confused. I see you open the duplicate special options and reset the settings but then you don't seem to set anything and I see the window close.
So what are you trying to do?
If you just want to mirror the torso then you can use the edit mesh > mirror tool.
Most people use duplicate special only if they want to create an instance of the mirrored half of the model.
But it is not clear what you are wanting to do.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675